1. Field of the Invention
The present invention relates to a solid-state imaging device and a driving control method and, more particularly, to a solid-state imaging device and a driving control method which allow imaging to be performed at a high speed using sub-sampling reading while preventing any reduction in the sensitivity of pixels.
2. Description of the Related Art
There is an accelerating trend toward CMOS (Complementary Metal Oxide Semiconductor) image sensors having a greater number of pixels. It takes a longer time for a CMOS image sensor to acquire one screen (one image) and it is therefore difficult to perform imaging at a high speed, the greater the number of pixels of the image sensor.
Approaches adopted to perform high speed imaging without changing resolution (without a reduction in resolution) include the use of signal processing such as an addition process. However, the signal processing must be adapted to a high frame rate, and a signal processing circuit for such a purpose is expensive. Further, the approach results in a cost increase because it necessities an additional memory.
Under the circumstance, sub-sampling reading is widely used as a method of performing high speed imaging at a low cost by taking advantage of the fact that CMOS image sensors have random accessibility to each pixel (for example, see JP-A-2008-167003 (Patent Document 1)).
Sub-sampling reading is a method of imaging in which a plurality pixels disposed in the form of a matrix are read out such that some of the pixels at predetermined intervals are skipped (sub-sampled) and in which one screen is formed by the pixels read out by surviving the sub-sampling. Since the number of pixels read out is reduced, an improved frame rate can be achieved although resolution is degraded.